context_memberships_url requirement

[pfurgal]

Hi Microsoft LTI Tool Team

This is about the LTI launch and HTTP 500 returned by the tool in the absence of the https://purl.imsglobal.org/spec/lti-nrps/claim/namesroleservice claim and its context_memberships_url attribute. The response body is empty, making it cumbersome to track down what's going on. I had to look at Azure Insight, then analyze the code (System.NullReferenceException at LtiAdvantageApi.cs:140)

I understand this is part of the troubleshooting guide, but can you please consider returning a descriptive error message?

Also, is there a way to launch a course without it? This is not part of the Core Spec. and therefore our platform doesn't support it. Does the tool require any other non-core services?

Thank you!